Late last month, the Manchester Airport installed a rear projection greeter designed to update travelers on airline regulations. It's not a hologram, but passengers have been attempting to put their hands through it and converse with it. London's Luton airport are installing similar virtual assistants called Holly and Graeme. These projections were built to speed up security checks, but it's unclear if they'll have any practical applications besides reminding travelers of the robot customs scene from Total Recall. Which is never a bad thing, mind you.